Direct electrical stimulation of parasympathetic nerves can activate the baroreflex, inducing a reduction of sympathetic nerve activity and reducing blood pressure by decreasing vascular resistance. Sympathetic inhibition and parasympathetic activation have been associated with reduced arrhythmia vulnerability following a myocardial infarction, presumably by increasing collateral perfusion of the acutely ischemic myocardium and decreasing myocardial damage. Modulation of the sympathetic and parasympathetic nervous system with neural stimulation has been shown to have positive clinical benefits, such as protecting the myocardium from further remodeling and predisposition to fatal arrhythmias following a myocardial infarction.
Different types of therapies can be delivered to treat a condition or to treat different conditions. For example, some neural stimulation therapies involve stimulating two or more neural stimulation targets. Additionally, it possible to deliver both neural stimulation (NS) therapy and cardiac rhythm management (CRM) therapy for some conditions. Some CRM therapies involve stimulating two or more cardiac sites. Some therapies apply pulses to measure an impedance across tissue, and use the impedance measurement to provide a sensed feedback to control the therapies. Thus, therapies can use multiple electrodes to apply current through tissue for the neural stimulation and CRM therapies, and for impedance measurements.